Geochemical-characterization-of-source-rocks,-crude-oils-and-gases-of-Northwest-Cuba_2004_Marine-and-Petroleum-Geology.pdf

Marine and Petroleum Geology 21 (2004) 195–214
ate/marpetgeo
Geochemical characterization of source rocks, crude oils
and gases of Northwest Cuba
C. Magniera,*, I. Morettia, . Lopezb, F. Gaumeta, . Lopezb, J. Letouzeya
aInstitut Franc¸ais du Pe´trole, 1-4 avenue du Bois Pre´au, Rueil Malmaison 92506, France
bCEINPET, Washington No. 169 Esq. A Churruca, Cerro, Ciudad de la Habana, . 12000, Cuba
Received 30 April 2003; received in revised form 12 November 2003; accepted 13 November 2003
Abstract
In order to characterize the Cuban petroleum system, we analyzed source rocks as well as crude oils and gases from carbonate producing
reservoirs from northwest onshore Cuban fields. The geochemical oil and gas characterizations were based on bulk analyses, chromatography
(liquid and gas), mass spectrometry and mass spectrometry-coupled to stable carbon isotope ratio determination. Analyses of sampled source
rocks intervals were performed with Rock Eval 6 and provided valuable data for the appraisal of the active petroleum system in Northwest
Cuba. Our paper focused on the ic semblance between carbonate reservoired crude oils and source rocks to assess the offshore extension
of the onshore Cuban carbonate petroleum system. Crude oils-source rocks and crude oils-offshore DSDP source rocks were correlated to a
common type of carbonate depositional environment. An understanding of the positions of carbonate crude oils, grouped in
families including heavy sulphur rich oils, light or mixed and biodegraded fluids helped to underline the different processes operating in the
reservoirs today. The high degree of anoxicity during anic matter deposition in the Upper Jurassic and Lower Cretaceous was
confirmed. We observed low hydrocarbon cracking levels and non biodegraded fluids of Type II/anic matter in Upper Jurassic and
Lower Cretaceous reservoirs, while shallower Tertiary reservoirs, although more mature were altered by microbial biodegradation. There